Question Alma Linux. Suddenly thunderbird not connecting to server (via plesk postfix)

[alexk345]

Server operating system version

alma linus

Plesk version and microupdate number

obsidian

Email client(thunderbird , outlook) not connecting to server (postfix)

But webmail.domain.com i was able to login and send and recieve emails.

Host is not solving it. I am stuck

Google is not helping on this.

I have immunify360 on.

 

[Peter Debik]

Please check whether Fail2Ban is blocking your own public IPv4 address (e.g. for too many false login attempts). You can either search for it in /var/log/fail2ban.log or search the list of banned ip addresses in Tools & Settings > Fail2Ban